The present invention relates to numerical control (NC) devices, and more particularly, to a method for displaying not only a code number and a message indicative of an alarm or an error condition which may occur during an operation of an apparatus controlled by the NC device but a manner how to escape from the alarm or error conditions on a CRT display for a numerical control device.
FIG. 1 is a schematic diagram showing an NC system including a CRT 9 and a numerical control device 8 controlling the CRT 9. The numerical control device includes a keyboard 10 for inputting data and instructions and a paper tape reader 11 for reading an operation program and data from an NC tape.
FIG. 2 is a diagram showing an example of display image which displays a code number indicative of an alarm, an alarm message and the like in conventional NC system.
The conventional CRT displaying method in the numerical control device will be described hereinafter with reference to FIGS. 1 and 2. Assuming that an electric discharge machining apparatus is controlled by the numerical control device 8, the numerical control device 8 first analyzes an NC program prepared by an operator, which is read out from the NC tape by the paper tape reader 11. The electric discharge machining apparatus performs the machining operation to obtain the programmed machining shape. When, for example, an alarm indicating an H/W stroke end where the machine is cut out of machining area limit occurs during the machining operation, the machining operation is stopped immediately, and an alarm code number corresponding to the alarm is set in an alarm code number area of a memory.
When the operator selects such a display as shown in FIG. 2. The content of the alarm is displayed according to the following manner on the CRT 9. The corresponding alarm message is searched based on the alarm code number to display on the CRT, the alarm code number in an alarm code number displaying area 12 and the alarm message in an alarm message displaying area 13 thereof, respectively.
The conventional CRT displaying method of numerical control devices is disadvantageous in that it takes long time to escape from an alarm or error condition because an operator's escaping operation is not performed until analyzing messages displayed on the CRT 9 or reading an instruction manual.